The family vault of the Percy family, dukes of Northumberland, is in St Nicholas's chapel in Westminster Abbey.

Elizabeth, Duchess of Northumberland

A large white marble monument to Elizabeth, Duchess of Northumberland stands in this chapel. This was designed by Robert Adam and sculpted by Nicholas Read. It consists of a basement from which rise two pedestals surmounted by figures of Faith, holding a cross, and Hope, with an anchor, with a wide circular arch between them enclosing a tablet and supporting a sarcophagus. On this is a relief of the Duchess seated on a couch, distributing alms to the poor. Beneath is her motto 'Esperance en Dieu'. The background is a tall pyramid topped by a flaming urn and decorated with an heraldic roundel surmounted by a coronet. On the plinths of the pedestals are a small lion and a unicorn, together with inverted torches, crescents and festoons. The inscription reads:

"Near this place lies interred Elizabeth Percy, Duchess of Northumberland, in her own right Baroness Percy, Lucy, Poynings, Fitz Payne, Bryan & Latimer, sole heiress of Algernon, Duke of Somerset & of the ancient Earls of Northumberland. She inherited all their great & noble qualities, with every amiable & benevolent virtue. By her marriage with Hugh, duke of Northumberland, she had issue Hugh, Earl Percy, Lady F.Eliz. Percy, whose died in 1761, Lord Algernon Percy. Having lived long, an ornament of courts, an honour to her country, & patern to the great, a protectress of the poor, ever distinguished for the most tender affection for her family & friends, she died December 5th 1776 aged sixty, universally beloved, revered, lamented. The Duke of Northumberland, inconsolable for the loss of the best of wives, hath erected this monument to her beloved memory"

Her parents were Algernon, 7th Duke of Somerset and his wife Frances (Thynne). In 1740 she married Hugh Smithson, who became 1st Duke of Northumberland. Hugh, a politician, son of Langdale Smithson, changed his surname to Percy in 1750. He was Lord Chamberlain to Queen Charlotte, Fellow of the Royal Society and a trustee of the British Museum. Elizabeth died at Northumberland House in London. Two of Hugh's illegitimate daughters, Philadelphia and Dorothy, were buried in the south transept of the Abbey.

Her son Hugh succeeded as 2nd Duke in 1786 and he married Anne, daughter of John Stuart, 3rd Earl of Bute (divorced). His second wife was Frances (Burrell). He was a Lt.Colonel in the Grenadier Guards and served in North America, taking part in the storming of Fort Washington and was in charge of the Rhode Island garrison when General Clinton returned to England. Also Member of Parliament for Westminster and one of the richest men in England.

Burials in the Northumberland vault.

In 1970 a list of those buried in the Northumberland vault were painted on the base of her monument (and has been kept updated):

Agnes, wife of Major General F.T.Buller daughter of 2nd Duke of Northumberland 1856

Algernon, 4th Duke of Northumberland 1865

Charlotte Florentia, widow of 3rd Duke of Northumberland 1866

George, 5th Duke of Northumberland 1867

Henry Hugh Manvers, son of 5th Duke of Northumberland 1877

Louisa, daughter of 5th Duke of Northumberland 1883,

Louisa, wife of 6th Duke of Northumberland 1890

Algernon George, 6th Duke of Northumberland 1899

Alan Ian, 8th Duke of Northumberland 1930

Helen Magdalen, widow of 8th Duke of Northumberland 1965

Hugh, 10th Duke of Northumberland 1988

Elizabeth, widow of 10th Duke of Northumberland, 2012".

Lord George Seymour, Viscount Beauchamp was buried on 6 July 1745, only son of Algernon and sister of Elizabeth Duchess of Northumberland. He died aged 19 of smallpox.

Hugh, 3rd Duke, was a son of Hugh and his wife Frances and was a Member of Parliament, Knight of the Garter, Ambassador Extraordinary to the King of France and Viceroy of Ireland. His wife was Charlotte (Gilbert), formerly a governess to Princess (later) Queen Victoria.

Algernon, the 4th Duke was born in 1792 at Syon House in London, a son of Hugh, the 2nd Duke and Frances. Joining the Navy at an early age he served in the Mediterranean at Toulon in 1808. In 1862 he was made an Admiral. He had a great interest in collecting artefacts in Egypt and financed astronomy projects and restored Alnwick Castle. His wife was Lady Eleanor Grosvenor. HIs body lay in state at Alnwick and then Northumberland House in London before burial in the vault.

George, 5th Duke was cousin to the 4th Duke and was a Member of Parliament, a Lord of the Treasury and served in the army as a volunteer. He married Louisa Stuart Wortley Mackenzie.

General Lord Henry Percy d.1877 (son of George, 5th duke) served in the Grenadier Guards and in Canada and was later a Member of Parliament. He was awarded the Victoria Cross for his action in the Crimean War at the battle of Inkerman when he led many trapped men through the Russian batteries to safety. He died unmarried.

Algernon, 6th Duke was a Captain in the Grenadier Foot Guards, Member of Parliament, a Lord of the Admiralty and Vice President of the Board of Trade among many other posts. He married in 1845 Louisa Drummond.

Alan, 8th Duke, politician, served in the Grenadier Guards and saw action in South Africa and in Egypt. Later he was aide de camp to the governor general of Canada. His wife was Lady Helen Gordon-Lennox. He re-joined at the outbreak of the Great War and sent reports from the Front for the newspapers. Later he was President of the Royal Institution and died in London on 23 August 1930.

Hugh, 10th Duke, was born in 1914 a son of the 8th Duke and his wife Lady Helen Gordon-Lennox and succeeded his brother, who was killed in action in 1940. He married Lady Elizabeth Montagu Douglas Scott.and served in the army. His interests were in agriculture and horses.

Many other members of the family are buried at the family seat, Alnwick Castle in Northumberland.

Isabella, Countess of Beverley

In this chapel is a simple mural monument by Joseph Nollekens to Isabella and the inscription reads: